Hey everyone, fairly knowledgeable with the 4.0 and running concerns, but having an issue with mine that I cannot figure out. Long story short, I bought this old POS Ranger for a bush rig, slapped a 4" sus lift, 3" body lift, new brakes, lines, joints, the works. I had the cab off, so like most everyone with the cab off would do, I took the chance to give the vehicle a good "under hood" bath. Yes I masked everything off, never got close to electrical to chance damaging anything etc. I'm a small engine mechanic/welder by trade, so I mostly know what to and what not to do when it comes to this stuff.

After the truck was complete, it would fire right up and run great, aside from a high idle which I found to be the EGR tube seal (replaced + all good now) Once that issue was fixed, another one come up. It WILL NOT restart after it's been running. It floods out very badly, runs rough, generally not happy. Here's what I've done:

-Replaced plugs and wires (double and triple checked routing and order, and had an extra set of eyes do the same)
-Checked the FPR for function and any bypassing through diaphragm
-Checked fuel pressure KOEO and KOER (in spec)
-Replaced coil pack with a good known spare I had
-Removed and cleaned MAF sensor

The truck is throwing no engine lights, and nothing is displaying if I plug it in. It'll fire up cold no problem, but when I shut it off, I have to do the "Flooded Engine" procedure (hold it to the floor) for about 7-10 seconds before it'll finally stumble on its way. It's soaked coming out the exhaust and black smoke indicating flooding. WTF is going on, any insight is appreciated, want to test this thing out!

 

Welcome to the forum

Always good to include the year of the Ranger, 1996?

ECT(engine coolant temp) sensor sets CHOKE mode, Rich running when engine is cold
It reads like this is more than just CHOKE Mode but thought I would mention it

Did you check the vacuum line on the FPR?

O2 sensor are the only sensors that wear out, they run out of the chemicals to detect oxygen in the exhaust, 100k miles or 12 years which ever comes first
O2s generate their own voltage
0.1volt high oxygen
0.9volt low oxygen
As the run out of chemicals the voltage drops, and low voltage = FALSE Lean, so computer runs engine much Richer than it needs to be, this sets no codes because computer only has the O2 sensors and nothing else to compare the air/fuel mix with
And the absence of "Rich codes" means computer thinks everything is "OK"

You can do Clear Flooded Engine test
Turn on key
Press gas pedal down to the floor all the way(this turns OFF fuel injectors, 0rpm + WOT = no injector pulses)
Try to start engine
Should just crank, it has spark but no fuel

If it starts/fires then could have a leaking injector, but no "rich codes" so a puzzler

If it starts check throttle cable, you may not be getting WOT(wide open throttle) on the throttle sensor
Use a stick against the seat to hold gas pedal down all the way
Go to the engine and see if you can manually open the throttle more, if so then Google: Ranger throttle cable mod
Easy fix
Then retest


And ultimately it could be a computer issue, the rich mix should cause codes to be set, and thats not happening, so if O2 sensors are newer then computer is screwing up the mix because of an internal fault